When manufacturing a heat exchanger used for example in a domestic air conditioner, a tube expanding apparatus is used to expand a heat-exchanging tube that passes through a fin layer, in which a plurality of fins are stacked, so as to integrate the fins and the heat-exchanging tube.
With this type of tube expanding apparatus, in some cases a so-called “avec” phenomenon occurs where the fins become tightly attached to one another due to the heat-exchanging tube shrinking in the length direction when the tube is expanded.
To prevent this “avec phenomenon”, as one example, Patent Document 1 described below proposes a tube expanding apparatus that uses the chucking apparatus depicted in FIG. 8 to grip a protruding portion of the heat-exchanging tube that protrudes from the fin layer and expands the heat-exchanging tube to integrate the tube and the fins.
With a tube expanding apparatus that is equipped with the chucking apparatus depicted in FIG. 8, the protruding portion of a heat-exchanging tube 104 that passes through a fin layer 102, in which fins 100, 100 are stacked, and protrudes from one side of the fin layer 102 is inserted inside a grip portion 106a of a chucking sleeve 106 whose outer circumferential surface is squeezed using a clamping sleeve 109. A cylindrical inner sleeve 108, which is formed of a spring member or the like so as to be elastic, is inserted into the protruding portion of the heat-exchanging tube 104.
A tube expanding billet 112 that is attached onto a front end of a mandrel 110 is inserted into the protruding portion of the heat-exchanging tube 104 so that the protruding portion of the heat-exchanging tube 104 is expanded via the inner sleeve 108. The outer circumferential surface of the expanded protruding portion of the heat-exchanging tube 104 that has been expanded in this way is gripped by the inner wall surface of the grip portion 106a of the chucking sleeve 106.
After this, the expanded protruding portion remains gripped by the grip portion 106a of the chucking sleeve 106 and a yet-unexpanded part of the heat-exchanging tube 104 is expanded by the tube expanding billet 112, thereby integrating the heat-exchanging tube 104 and the fins 100.
Patent Document 1    Japanese Laid-Open Patent Publication No. H09-99334